This invention relates to a drive voltage generating circuit employed in a drive unit such as a liquid crystal display or the like, and particularly to a drive voltage generating circuit suitable for providing integrated circuitry, which changes a drive voltage to adjust contrast.
As a drive voltage generating circuit used in a liquid crystal panel, there is known one described in Japanese Laid-Open Patent Application No. 5-257120, for example. Since a bias potential control circuit is added to the drive voltage generating circuit, the drive voltage generating circuit eliminates the need for provision of contrast adjusting variable resistors which have heretofore been used as external parts. Further, temperature coefficients of resistors forming a bias circuit of the drive voltage generating circuit can be made identical to those of resistors of the bias potential control circuit so as to cancel variations in resistor, which take place according to temperature
However, the above drive voltage generating circuit causes a trade-off between power consumption and the quality of a reproduced image if one attempts to make improvements in the two.